this video will focus on mature connective tissues dense loose and blood there are five groups of ature connective tissues loose connective tissue dense connective tissue cartilage bone and liquid think about each of these groups as something that you are purchased in this store so for example loose would be something like chips dense might be soda cartilage might be candy bone might be bread and liquid might be ice cream so there's not just one flavor of chips so for loose we have three flavors for dense we have three for cartilage we have 30 for bone we have two and for liquid we up to so these categories up here these categories are giving a description of the overview of the category so for loose connective tissue the fibers are going to be loosely intertwined and very visible cells for dense connective tissue the fibers are going to be tightly packed so the cells aren't as visible because they're smushed between the fibers and cartilage we'll discuss in a little bit more detail once we get to that category so we will start first with loose there are three types of loose or three flavors there's areolar adipose and reticular air other connective tissue I like to refer to as the scotch tape of the body this connective tissue is the one that you think about when you think about people saying connective tissue connects this tissue is found between multiple changes of organs our tissues themself so we find areolar in the area where we go from the epidermis into the dermis we find areolar with its buddy adipose tissue if you've ever taken the skin off of a chicken you might see a silvery white layer separating from the meat that is areola if in your general biology course you dissected a rat and you remove the skin of the rat to see the muscles you saw a whitish silverish thin layer that is areolar it keeps things held together but it's not very strong now areola has many different cells in it and it also has all three fiber types however you don't see the fiber types very well so we usually only concentrate on two fibers collagen and elastic now when we look at this picture what we'll notice is that there are lots of fibers kind of loosely woven almost like spider webs and we can see tons of different cells in the background what we're mostly seeing though are we're mostly seeing the nuclei of the cell now for the fibers what happens is your elastic fibers are these nice thin darker lines that kind of look like pencil lines and they almost popping forward or as the collagen fibers are going to be more in the background whoops to draw that one far enough more in the background and they're usually in groups so you're not seeing an individual fiber and they're almost forming that background color or the background stage the collagen fiber does lend itself strength and then with the elastic it allows this issue to stretch and recoil so extensibility and elasticity now when we look at the different cell types when we look at cells a lot of times it's very hard to see the cell membrane so we often are just looking at the shape of the cell or the shape of the nucleus to be specific so there's gonna be two cells that we're going to want you to be able to identify these two cells are going to be fibroblasts and one that's not labeled on here is a macrophage fibroblast cells are going to be oval in nature so we're gonna see an oval nucleus so here is a fibroblast there's a fibroblast here is a fibroblasts so we can see their nucleus shape and that's going to be a little bit different than what we consider macrophages which are going to be a more rounded nucleus macrophages are modified white blood cells and they're basically the job is to eat their large cells that will eat and take away other debris so they're kind of like garbage cans and then the fibroblasts are going to produce many of the fibers the next loose connective tissue is adipose now while adipose is often people's favorite to identify it's often misidentified when being assessed now adipose tissue is what we know is our fat tissue so when we look at this whole picture this whole picture is showing us adipose tissue adipose tissue is made up of cells turns adipose sites so each of these marshmallows are considered adipose sites in the adipose sites is going to be a big fat droplet lipid dropp'd fat storage area that is so large that is pushing all of the organelles to the side so all you really see is a nucleus smush to the side and this is where the fat droplet our lipid drop is adipose tissue is very vascular so often it's hard to get in focus because it is white in appearance but because the blood vessels stain so well often you focus on the blood vessel and then you start scanning the slide until you find the adipose tissue adipose tissue is going to be found surrounding organs for protection we find it in your subcutaneous layer your subcutaneous layer has many many names we also call it the sub-q and we also call it the hypodermis this is your fat layer of the body cushion protection energy storage and we also find adipose tissue in your yellow bone marrow in the diathesis this does not appear till around puberty now you actually have different types of fat in your body what we're looking at right now is white fat but when you're born you're gonna have something called brown adipose tissue or brown fat and this is going to be in high amounts in newborns they're going to have more mitochondria and be even more vascularized and this allows for a better thermogenesis or heat production for newborns as the newborn starts to develop and grow brown fat slowly is taken over my wife at our last loose connective tissue is reticular when I look at reticular I see grapes blueberry clusters some people say cherry blossoms reticular again we can see lots of cells very visible with loosely intertwined fibers these based off their name reticular tissue or reticular fibers and these are going to be short and wavy and we find these reticular fibers in areas that need extra support and reinforcements so we find the ticular tissue in small organs such as lymph the slain but it also supports red bone marrow which is where your blood is produced reticular tissue is going to have what we call reticular sites so each of these cells right here these are known as reticular sites so those are the three Lucis areolar adipose and reticular the next are going to be your deaths you're dense connective tissues get their name because the fibers are so densely packed that we don't see these cells as easily so the cells again are going to be smushed between the fibers the three densities are dense regular dense irregular and elastic connective tissue dense regular gets its name because the collagen fibers are running in a regular direction so they can be running transversely they can be running rectus they can be running at an angle oblique but they're all running in the same direction so when we look at this picture all the fibers are going left to right in this picture these are not individual collagen fibers as much as they are bundles and then what we also see our fibroblast nuclei smushed between them like pancakes you will have a lot of fibroblasts in these particular tissues because there's lots of fibers now dense regular is very strong but it's only strong in the direction it runs so in this particular picture we see it running left to right so if anything is pulling it this way it's going to be strong in this direction but the minute something tries to pull it like this our light tries to pull it like this it's going to be easily torn we find this in tendons and ligaments and you hear a lot about ACL injuries PCL MCL and these injuries usually happen when force is hitting the tendon or the ligament at it at an angle that they normally don't run now in comparison the dense regular dense irregular gets its name because the collagen fibers are going in all different directions so to me this looks like tenderized meat we find dense irregular in the dermis and the bulk of the dermis and this is where your dermis your skin gets the strength from think about moving your skin in all different directions and these collagen fibers are going in all different directions so no matter what direction they are pulled they're providing strength to the structure we also find dense irregular in the sclera of the eye and when dissections of eyeballs are done it's really tough to get through that white section of the eye dense irregular is also going to be making up the perichondrium and the periosteum both of these are sheets of tissue that surround bone or cartilage the less dense tissue is dense connective sorry elastic connective tissue elastic connective tissue to me looks like either lasagna or turkey bacon I always say it depends on the stain and this stain is relatively dark so I would say this one was lasagna and if you get a really light stain I usually say it's turkey bacon because of its name elastic connective tissue you know that it's going to have elastic fibers however elastics buddy is collagen and so we often see those bundle together the elastic fibers are going to look like the foreground popping forward whereas the collagen fibers are going to almost take this background filling this is really important that we have strength with this tissue because this tissue is going to allow a lot of stretching and recoiling we're going to find it in a lot of blood vessels the lungs so this tissue is really important for its strength and it's and its merit and functionality so dense connected we had dense regular density regular and elastic connective tissue our next group is going to be blood blood is a liquid connective tissue there are actually two liquid connective tissues blood and lymph but blood is the only one that will be covered in this particular class now blood what we call a liquid connective tissue it is liquid but it also has solid parts if you remember all connective tissues have to have cells and a matrix so when we look at blood the matrix of blood is going to be your plasma and in this particular micrograph all of this is the plasmid what's white in the background then we're gonna have your cells now there are three types of cells are what we actually call formed elements that are found in blood the first type is going to be your with recites your with recites are the red blood cells however since they are enucleated without a nucleus they're actually not considered real cells they're considered formed elements so when we look at a blood cell all of these that are kind of pinkish red those are all your with our sites and you'll notice that the middle almost looks empty it almost looks clear and that's because these cells are what we call biconcave and so the middle of these cells squeezes in and that gives us that membrane 2 membrane appearance so we're not seeing they fill or on the outside you're with recites function main function is to help transport gases specifically oxygen the next are going to be leukocytes there are lots leukocytes but for this particular class you're not going to learn the types such as neutrophils asana fills you're gonna just learn leukocytes these are white blood cells and they're much larger than the ureter sites but the big key is that they have a nucleus and their function is immunity they help us fight off infection to keep healthy now the last formed element is not even actually even a cell but it's called a thrombus I'd and these are platelets okay thrombocytes or platelets are used for blood clotting and they're actually just little pieces of the cell so when you look at this picture they're really tiny so you don't really even know if they're dirt or if they're actually a thrombosed site but this is a thrombus site blown up a lot so this is about three to four times larger than you'll see it on the microscopes but this is a thrombus line it's really just a segment our fragment of another cell